Apparatus for testing earth formations

ABSTRACT

In the representative embodiment of the new and improved apparatus for testing earth formations disclosed herein, fluidadmitting means are selectively extended into sealing engagement with a potentially-producible earth formation and a selectivelyoperable valve on the fluid-admitting means is opened to place a filtering medium arranged on the fluid-admitting means into communication with the isolated formation without inducing the erosion of loose formation materials as the testing is conducted. Then, when the testing is completed, the fluid-admitting means are retracted and the valve is reclosed in readiness for subsequent testing operations.

Unite States Patent Whitten Jan. 1, 1974 [5 APPARATUS FOR TESTING EARTH3,577,781 5/1971 Lcbourg 73/152 O T S 3,653,436 4/1972 Anderson et a1.166/100 [75] Inventor: Frank R. whitten, Houston, Tex. PrimaryExaminermjerry W. Myracle [73] Assignee: Schlumberger TechnologyAttorney-Ernest R. Archambeau, Jr. et a1.

Corporation, New York, NY.

[22] Filed: Dec. 8, 1972 [57] ABSTRACT [21] Appl M 313,240 In therepresentative embodiment of the new and improved apparatus for testingearth formations disclosed herein, fluid-admitting means are selectively[2%] 73/151552, 162900 extended into Sealing engagement with aPotentially d producible earth formation and a selectively-operable 1 0care 73 1 valve on the fluid-admitting means is opened to place afiltering medium arranged on the fluid-admitting 56 R f d means intocommunication with the isolated formation 1 e erences me withoutinducing the erosion of loose formation mate- UNITED STATES PATENTSrials as the testing is conducted. Then, when the test- 3,0ll,55412/1961 Desbrandes et a]. '166/100 ing is completed, the fluid-admittingmeans are re- 3,352,36l l1/l967 Urbanosky l66/l00 tracted and the valveis r'eclosed in readiness for sub- Whitten sequent testing perations3,530,933 9/1970 Whitten 166/100 3,565,169 2/1971 Bell 166/100 21Claims, 7 Drawing Figures '91 37-3781030 1/ 93 1 1 1 1 1 1 LL IT E 92ELECTRICAL j CONTROLS 59" 1 94 170/04 1 I 1 95 86- 960 11 1 Luce, 701/11968 J 1 0 1030 1 1% c1 728 113 1. 726 I -722 wafi 117 ,121 E 710 L JPATENTEUJAH 1 I974,

POWER SUPPLY sum 10F 6 --------RECORDER FIG. 1

PAIENIEQJAH 1 1914 3.782.191

' sum-qr 2 or e I 37-378 103a FIG; 2A v 1/ 3 ELECTRICAL CONTROLSPAIENTEDJAH 914 3.782.191

FROM 20 (FIG. 5B)

- l APPARATUS FOR TESTING EARTH FORMATIONS l-leretofore, the typicalwireline formation testers (such as the tool disclosed in U.S. Pat. No.3,01 1,554) which have been most successful in commercial service havebeen limited to attempting only a single test of one selected formationinterval. Those skilled in the art will appreciate that once one ofthese typical tools is positioned in a well bore and a sample or testingoperation is initiated, the tool cannot be again operated without firstremoving it from the well bore and reconditioning various toolcomponents for another run. Thus, even should it be quickly realizedthat a particular sampling or testing operation already underway willprobably be unsuccessful, the operator has no choice except todiscontinue the operation and then return the tool to the surface. Thisobviously results in a needless loss of time and expense which wouldusually be avoided if another attempt could be made without having toremove the tool from the well bore.

One of the most significant problems which have heretofore prevented theproduction of a commercially successful repetitively-operableformation-testing tool has been in providing a suitable arrangement forreliably establishing fluid or pressure communication with incompetentor unconsolidated earth formations. Although the several new andimproved testing tools respectively shown in U.S. Pat. No. 3,352,361,U.S. Pat. No. 3,530,933, U.S. Pat. No. 3,565,169 and U.S. Pat. No.3,653,436 are especially arranged for testing unconsolidated formations,for one reason or another these tools are not adapted for performingmore than one testing operation during a single run in a given wellbore. For example, as described in these patents, each of these new andimproved testing tools employs a tubular sampling member which iscooperatively associated with a filtering medium for preventing theunwanted entrance of unconsolidated formation materials into the testingtool.

Accordingly, it is an object of the present invention to provide new andimprovded formation-testing apparatus for reliably obtaining multiplemeasurements of one or more fluid or formation characteristics as wellas selectively collecting one or more samples of connate fluids, ifdesired, from earth formations of any nature.

This and other objects of the present invention are attained byprovidingformation-testing apparatus having selectively-extendiblefluid-admitting means adapted for movement into sealing engagement witha potentially-producible earth formation to isolate a portion thereoffrom the well bore fluids. To limit loose formation materials which maybe present in the isolated formation from plugging the fluid-admittingmeans, filtering means are disposed in the fluidadmitting means.Selectively-operable valve means are cooperatively arranged in thefluid-admitting means for selective movement between an open position toopen communication between an isolated earth formation and the filteringmeans and a normal closed position blocking the filtering means.

The novel features of the present invention are set forth withparticularity in the appended claims. The invention, together withfurther objects and advantagesv thereof, may be best understood by wayof the following description of exemplary apparatus employing theprinciples of the invention as illustrated in the accompanying drawings,in which:

FIG. 1 depicts the surface and downhole portions of new and improvedformation-testing apparatus including a preferred embodiment offluid-admitting means incorporating the principles of the presentinvention;

FIGS. 2A and 23 together show a somewhatschematic representation of theformation-testing tool illustrated in FIG. 1 as the tool will appear inits initial operating position; and

FIGS. 3-5 respectively depict the successive positions of variouscomponents of the new and improved tool shown in FIGS. 2A and 28 duringthe course of a typical testing sand sampling operation to illustratethe operation of the fluid-admitting means of the present invention.

Turning now to FIG. 1, a preferred embodiment of a new and improvedsampling and measuring tool 10 incorporating the principles of thepresent invention is shown as it will appear during the course of atypical measuring and sampling operation in a well bore such as aborehole l1 penetrating one or more earth formations as at 12 and 13. Asillustrated, the tool 10 is suspended in the borehole 11 from the lowerend of a typical multiconductor cable 14 that is spooled in the usualfashion on a suitable winch (not shown) at the surface and coupled tothe surface portion of a tool-control system 15 as well as typicalrecording and indicating apparatus 16 and a power supply 17. In itspreferred embodiment, the tool 10 includes an elongated body 18 whichencloses the downhole portion of the tool control system 15 and carriesselectively-extendible toolanchoring means 19 arranged on opposite sidesof the body from new and improved fluid-admitting means 20 as well asone or more tandemly-coupled fluidcollecting chambers 21 and 22.

As is explained in greater detail in a copending application Ser. No.313,235 filed Dec. 8, 1972. by Harold J. Urbanosky filed simultaneouslyherewith, the new and improved formation-testing tool 10 and the controlsystem 15 are cooperatively arranged so that, upon command from thesurface, the tool can be selectively placed in any one or more of fiveselected operating positions. As will be subsequently described briefly,the control system 15 will function to either successively place thetool 10 in one or more of these positions or else cycle the tool betweenselected ones of these oper ating positions. These five operatingpositions are simply achieved by selectively moving suitable controlswitches, as schematically represented at 23 and 24, included in thesurface portion of the system 15 to various switching positions, as at25-30, so as to selectively apply power to different conductors 31-37 inthe cable 14.

Turning now to FIGS. 2A and 2B, the entire downhole portion of thecontrol system 15 as well as the tool-anchoring means 19, thefluid-admitting means 20 and the fluid-collecting chambers 21 and 22 areschematically illustrated with their several elements or componentsdepicted as they will respectively be arranged when the new and improvedtool 10 is fully retracted and the switches 23 and 24 are in their firstor of operatingpositions 25. In the preferred embodiment of theselectively-extendible tool-anchoring means 19 schematically illustratedin FIG. 2A, an upright wallengaging anchor member 38 along the rear ofthe tool body 18 is coupled in a typical fashion to alongitudinally-spaced pair of laterally-movable piston actuators 39 and40 of a typical design mounted transversely on the tool body 18. As willbe subsequently explained, the lateral extension and retraction of thewall-engaging member 38 in relation to the rear of the tool body 18 iscontrolled by the control system which is operatively arranged toselectively admit and discharge a pressured hydraulic fluid to and fromthe piston actuators 39 and 40.

The fluid-admitting means of the present invention are cooperativelyarranged for sealing-off or isolating selected portions of the wall ofthe borehole 11; and, once a selected portion of the borehole wall ispacked-off or isolated from the well bore fluids, establishing pressureor fluid communication with the adjacent earth formations. As depictedin FIG. 2A, in the preferred embodiment, the fluid-admitting means 20include an annular elastomeric sealing pad 41 mounted on the forwardface of an upright support member or plate 42 that is coupled to alongitudinally-spaced pair of laterally-movable piston actuators 43 and44 respectively arranged transversely on the tool body 18 for moving thesealing pad in relation to the forward side ofthe tool body.Accordingly, as the control system 15 selectively supplies a pressuredhydraulic fluid to the piston actuators 43 and 44, the sealing pad 41will be moved laterally between a retracted position adjacent to theforward side of the tool body 18 and an advanced or forwardly-extendedposition.

By arranging the annular sealing member 41 on the opposite side of thetool body 18 from the wallengaging member 38, the lateral extension ofthese two members will, of course, be effective for urging the sealingpad into sealing engagement with the adjacent wall of the borehole 11and anchoring the tool 10 each time the piston actuators 39, 40, 43 and44 are extended. It will, however, be appreciated that the wallengagingmember 38 as well as its piston actuators 39 and 40 would not be neededif the effective stroke of the piston actuators 43 and 44 would besufficient for assuring that the sealing member 41 can be extended intofirm sealing engagement with one wall of the borehole 11 with the rearof the tool body 18 securely anchored against the opposite wall of theborehole. Conversely, the piston actuators 43 and 44 could be similarlyomitted where the extension of the wall-engaging member 38 alone wouldbe effective for moving the other side of the tool body 18 forwardlytoward one wall of the borehole 11 to place the sealing pad 41 into firmsealing engagement therewith. However, in the preferred embodiment ofthe formation-testing tool 10, both the tool-anchoring means 19 and thefluidadmitting means 20 are made selectively extendible to enable thetool to be operated in boreholes of substantial diameter. This preferreddesign of the tool 10, of course, results in the overall stroke of thepiston actuators 39 and 40 and the piston actuators 43 and 44 being keptto a minimum so as to reduce the overall diameter of the tool body 18.

To conduct connate fluids into the new and improved tool 10, thefluid-admitting means 20 of the present invention further include anenlarged tubular member 45 having an open forward portion coaxiallydisposed within the sealing pad 41 and a closed rear portion which isslidably mounted within a larger tubular member 46 secured to the rearface of the plate 42 and extended rearwardly therefrom. By arranging thenose of the tubular fluid-admitting member 45 to normally protrude ashort distance ahead of the forward face of the sealing pad 41,extension of the fluid-admitting means 20 will engage the forward end ofthe fluid-admitting member with the adjacent surface of the wall of theborehole 11 just before the annular sealing pad is also forcedthereagainst for isolating that portion of the borehole wall as well asthe nose of the fluid-admitting member from the well bore fluids. Thesignificance of this sequence of engagement will be subsequentlyexplained. To selectively move the tubular fluidadmitting member 45 inrelation to the enlarged outer member 46, the smaller tubular member isslidably disposed within the outer tubular member and fluidly sealed inrelation thereto as by sealing members 47 and 48 on inwardly-enlargedend portions 49 and 50 of the outer member and a sealing member 51 on anenlarged-diameter intermediate portion 52 of the inner member.

Accordingly, it will be appreciated that by virtue of the sealingmembers 47, 48 and 51, enclosed piston chambers 53 and 54 are definedwithin the outer tubular member 46 and on opposite sides of theoutwardlyenlarged portion 52 of the inner tubular member 45 which, ofcourse, functions as a piston member. Thus, by increasing the hydraulicpressure in the rearward chamber 53, the fluid-admitting member 45 willbe moved forwardly in relation to the outer tubular member 46 as well asto the sealing pad 41. Conversely, upon the application of an increasedhydraulic pressure to the forward piston chamber 54, the fluid-admittingmember 45 will be retracted in relation to the outer member 46 and thesealing pad 41.

Pressure or fluid communication with the fluidadmitting means 20 of thepresent invention is controlled by means such as a generally-cylindricalvalve member 55 which is coaxially disposed within the fluidadmittingmember 45 and cooperatively arranged for axial movement therein betweena retracted or open position and the illustrated advanced or closedposition where the enlarged forward end 56 of the valve member issubstantially, if not altogether, sealingly engaged with the forwardmostinterior portion of the fluidadmitting member. To support the valvemember 55, the rearward portion of the valve member is axially hollowed,as at 57, and coaxially disposed over a tubular member 58 projectingforwardly from the transverse wall 59 closing the rear end of thefluid-admitting member 45. The axial bore 57 is reduced and extendedforwardly along the valve member 55 to a termination with one or moretransverse fluid passages 60 in the forward portion of the valve memberjust behind its enlarged head 56.

To provide piston means for selectively moving the valve member 55 inrelation to the fluid-admitting member 45, the rearward portion of thevalve member is enlarged, as at 61, and outer and inner sealing members62 and 63 are coaxially disposed thereon and respectively sealinglyengaged with the interior of the fluid-admitting member and the exteriorof the forwardly-extending tubular member 58. A sealing member 64mounted around the intermediate portion of the valve member 55 andsealingly engaged with the interior wall of the adjacent portion of thefluid-admitting member 45 fluidly seals the valve member in relation tothe fluid-admitting member. Accordingly, it will be appreciated that byincreasing the hydraulic pressure in the enlarged piston chamber 65defined to the rear of the enlarged valve portion 61 which serves as apiston member, the valve member 55 will be moved forwardly in relationto the fluid-admitting member 45. Conversely, upon application of anincreased hydraulic pressure to the forward piston chamber 66 definedbetween the sealing members 62 and 64, the valve member 55 will be movedrearwardly along the forwardlyprojecting tubular member 58 so as toretract the valve member in relation to the fluid-admitting member 45.

Those skilled in the art will, of course, appreciate that many earthformations, as at 112, are relatively unconsolidated and are, therefore,readily eroded by the withdrawal of connate fluids. Thus, to prevent anysignificant erosion of such unconsolidated formation materials, thefluid-admitting member 45 is arranged to define an internal annularspace 67 and a flow passage 68 in the forward portion of thefluid-admitting member, and a tubular screen 69 with slits or aperturesof suitable fineness is coaxially mounted around the annular space. Inthis manner, when the valve member 55 is retracted, formation fluidswill be compelled to pass through the exposed forward portion of thescreen 69 ahead of the enlarged head 56, into the annular space 67, andthen through the fluid passage 60 into the fluid passage 57 and thetubular member 58. Thus, as the valve member 55 is retracted, shouldloose or unconsolidated formation materials be eroded from a formationas connate fluids are withdrawn therefrom, the materials will be stoppedby the exposed portion of the screen 69 ahead of the enlarged head 56 ofthe valve member thereby quickly forming a permeable barrier to preventthe continued erosion of loose formation materials once the valve memberhalts.

A sample or flow line 70 is cooperatively arranged in theformation-testing tool and has one end coupled, as by a flexible conduit71, to the fluid-admitting means and its other end terminated in a pairof branch conduits 72 and 73 respectively coupled to the fluidcollectingchambers 21 and 22. To control the communication between thefluid-admitting means 20 and the fluid-collecting chambers 21 and 22,normally-closed flow-control valves 74-76 of a similar or identicaldesign are arranged respectively in the flow line 70 and in the branchconduits 72 and 73 leading to the sample chambers. For reasons whichwill subsequently be described in greater detail, a normally-opencontrol valve 77 which is similar to the normally-closed control valves74-76 is cooperatively arranged in a branch conduit 78 for selectivelycontrolling communication between the well bore fluids exterior of thetool 10 and the upper portion of the flow line 70 extending between theflow-linecontrol valve 74 and the new and improved fluid-admitting means20.

As illustrated, the control valve 77 is comprised of a valve body 79cooperatively carrying a typical piston actuator 80 which is normallybiased to an elevated position by a spring 81 of a predeterminedstrength. A valve member 82 coupled to the piston actuator 80 iscooperatively arranged for blocking fluid communication between theinlet and outlet fluid ports of the control valve whenever the valvemember is moved to its lower position. The control valves 74-76 aresimilar to the control valve 77 except that a spring of selectedstrength "is respectively arranged in each for normally biasing each ofthese valve members to a closed position.

As shown in FIGS. 2A-2B; a branch conduit 83 is coupled to the flow lineat a convenient location between the sample chamber control valves and76 and the flow-line control valve 74, with this branch conduit beingterminated at an expansion chamber 84 of a predetermined volume. Areduced-diameter displacement piston 85 is operatively mounted in thechamber 84 and arranged to be moved between selected upper and lowerpositions therein by a typical piston actuator shown generally at 86.Accordingly, it will be appreciated that upon movement of thedisplacement piston 85 from its lower position as illustrated in FIG. 2Ato an elevated or upper position, the combined volume of whatever fluidsthat are then contained in the branch conduit 83 as well as in thatportion of the flow line 70 between the flow-line control valve 74 andthe sample chamber control valves 75 and 76 will be correspondinglyincreased.

As best seen in FIG. 2A, the preferred embodiment of the control system15 further includes a pump 87 that is coupled to a driving motor 88 andcooperatively arranged for pumping a suitable hydraulic fluid such asoil or the like from a reservoir 89 into a discharge or outlet line 90.Since the tool 10 is to be operated in well bores, as at 11, whichtypically contain dirty and usually corrosive fluids, the reservoir 89is preferably arranged to totally immerse the pump 87 and the motor 88in the clean hydraulic fluid. Inasmuch as the formation-testing tool 10must operate at extreme depths, the reservoir 89 is provided with aninlet 91 for well bore fluids and an isolating piston 92 is movablyarranged in the reservoir for maintaining the hydraulic fluid containedtherein at a pressure about equal to the hydraostatic pressure atwhatever depth the tool is then situated. A spring 93 is arranged to acton the piston 92 for maintaining the pressure of the hydraulic fluid inthe reservoir 89 at an increased level slightly above the well borehydrostatic pressure so as to at least minimize the influx of well borefluids into the reservoir. In addition to isolating the hydraulic fluidin the reservoir 89, the piston 92 will also be free to move as requiredto accommodate volumetric changes in the hydraulic fluid which may occurunder different well bore conditions. One or more inlets, as at 94 and95, are provided for returning hydraulic fluid from the control system15 to the reservoir 89 during the operation of the tool 10.

The fluid outlet line is divided into two major branch lines which arerespectively designated as the set line 96 and the retract line 97. Tocontrol the admission of hydraulic fluid to the set and retract lines 96and 97, a pair of normally-closed solenoidactuated valves 98 and 99 arecooperatively arranged to selectively admit hydraulic fluid to the twolines as the control switch 23 at the surface is selectively positioned;and a typical check valve 100 is arranged in the set" line 96 downstreamof the control valve 98 for preventing the reverse flow of the hydraulicfluid whenever the pressure in the set line is greater than that thenexisting in the fluid outlet line 90. Typical pressure switches 101-103are cooperatively arranged in the set and retract lines 96 and 97 forselectively discontinuing operation of the pump 87 whenever the pressureof the hydraulic fluid in either of these lines reaches a desiredoperating pressure and then restarting the pump whenever the pressuredrops below this value so as to maintain the line pressure within aselected operating range.

Since it is preferred that the pump 87 be a positivedisplacement type toachieve a rapid predictable rise in the operating pressures in the setand retract" lines 96 and 97 in a minimum length of time, the controlsystem 15 also provides for temporarily opening the outlet line 90 untilthe motor 88 has reached its rated operating speed. Accordingly, thecontrol system 15 is cooperatively arranged so that each time the pump87 is to be started, the control valve 99 (if it is not already open) aswell as a third normally-closed solenoidactuated valve 104 will betemporarily opened to bypass hydraulic fluid directly from the outputline 90 to the reservoir 89 by way of the return line 94. Once the motor88 has reached operating speed, the bypass valve 104 will, of course, bereclosed and either the set line control valve 98 or the retract linecontrol valve 99 will be selectively opened as required for thatparticular operational phase of the tool 10. It should be noted thatduring times that the retract line control valve 99 and the fluid-bypassvalve 104 are opened to allow the motor 88 to reach its operating speed,the check valve 100 will function to prevent the reverse flow ofhydraulic fluid from the set line 96 when the set line control valve 98is open.

Accordingly, it will be appreciated that the control system 15cooperates for selectively supplying pressured hydraulic fluid to theset" and retract" lines 96 and 97. Since the pressure switches 101 and102 respectively function only to limit the pressures in the set" andretract" lines to a selected maximum pressure range commensurate withthe rating of the pump 87, the new and improved control system 15 isfurther arranged to cooperatively regulate the pressure of the hydraulicfluid which is being supplied at various times to selected portions ofthe system. Although this regulation can be accomplished in differentmanners, it is preferred to employ a number of pressure-actuated controlvalves such as shown schematically at 105-108 in FIGS. 2A and 2B. Asshown in FIG. 2A, the control valve 105, for example, includes a valvebody 109 having a valve seat 110 coaxially arranged therein betweeninlet and outlet fluid ports. The upper portion of the valve body 109 isenlarged to provide a piston cylinder 111 carrying an actuating piston112 in coincidental alignment with the valve seat 110. A spring 113 of apredetermined strength is arranged for normally urging the actuatingpiston 112 toward the valve seat 110 and a control port 114 is providedfor admitting hydraulic fluid into the cylinder 111 at a sufficientpressure to overcome the force of this spring whenever the piston is tobe selectively moved away from the valve seat. Since the control system15 operates at pressures no less than the hydrostatic pressure of thewell bore fluids, a relief port 115 is provided in the valve body 109for communicating the space in the cylinder 111 above the actuatingpiston 112 with the reservoir 89. A valve member 116 complementallyshaped for seating engagement with the valve seat 110 is cooperativelycoupled to the actuating piston 112 as by an upright stem 117 which isslidably disposed in an axial bore 118 in the piston. A spring 119 ofselected strength is disposed in the axial bore 118 for normally urgingthe valve member 116 into seating engagement with the valve seat 110.

' Accordingly, in its operating position depicted in H6. 2A, the controlvalve 105 (as well as the valve 106) will simply function as anormally-closed check valve. That is to say, in this operating position,hydraulic fluid can flow only in a reverse direction whenever thepressure'at the valve outlet is sufficiently greater than the inletpressure to elevate the valve member 116 from the valve seat 110 againstthe predetermined closing force imposed by the spring 119. On the otherhand, when sufflcient fluid pressure is applied to the control port 114for elevating the actuating piston, opposed shoulders, as at 120, on thestem 117 and the piston 112 will engage for elevating the valve member116 from the valve seat 110.

As shown in FIGS. 2A and 28, it will be appreciated that the controlvalve 107 (as well as the valve 108) is similar to the control valve 105except that in the firstmentioned control valve, the valve member 121 ispreferably rigidly coupled to its associated actuating piston 122. Thus,the control valve 107 (as well as the valve 108) has no alternatechecking action allowing reverse flow and is simply a normally-closedpressure-actuated valve for selectively controlling fluid communicationbetween its inlet and outlet ports. Hereagain, the hydraulic pressure atwhich the control valve 107 (as well as the valve 108) is to selectivelyopen is governed by the predetermined strength of the spring 123normally biasing the valve member 121 to its closed position.

The set" line 96 downstream of the check valve is comprised of alow-pressure section 124 having one branch 125 coupled to the fluidinlet of the control valve 107 and another branch 126 which is coupledto the fluid inlet of the control valve to selectively supply hydraulicfluid to a high-pressure section 127 of the set line which is itselfterminated at the fluid inlet of the control valve 108. To regulate thesupply of hydraulic fluid from the low-pressure section 124 to thehigh-pressure section 127 of the set line 96, a pressure-communicatingline 128 is coupled between the low-pressure section and the controlport of the control valve 105. Accordingly, so long as the pressure ofthe hydraulic fluid in the low-pressure section of the set line 96remains below the predetermined actuating pressure required to open thecontrol valve 105, the high-pressure section 127 will be isolated fromthe lowpressure section 124. Conversely, once the hydraulic pressure inthe low-pressure line 124 reaches the predetermined actuating pressureof the valve 105, the control valve will open to admit the hydraulicfluid into the high-pressure line 127.

The control valves 107 and 108 are respectively arranged to selectivelycommunicate the low-pressure and high-pressure sections 124 and 127 ofthe set line 96 with the fluid reservoir, 89. To accomplish this, thecontrol ports of the two control valves 107 and 108 are each connectedto the retract line 97 by suitable pressure-communicating lines 129 and130. Thus, whenever the pressure in the retract" line 97 reaches theirrespective predetermined actuating levels, the control valves 107 and108 will be respectively opened to selectively communicate the twosections 124 and 127 of the set" line 96 with the reservoir 89 by way ofthe return line 94 coupled to the respective outlets of the two controlvalves.

As previously mentioned, in FIGS. 2A-2B the tool 10 and the sub-surfaceportion of the control system 15 are depicted as their severalcomponents will appear when the tool is retracted. At this point, thewallengaging member 38 and the sealing pad 41 are respectively retractedagainst the tool body 18 to facilitate passage of the tool 10 into theborehole l 1. To prepare the tool 10 for lowering into the borehole 11,the switches 23 and 24 are moved to their second or initializationpositions 26. At this point, the hydraulic pump 87 is started to raisethe pressure in the retract line 97 to a selected maximum to be certainthat the pad 41 and the wall-engaging member 38 are fully retracted. Aspreviously mentioned, the control valves 99 and 104 will be momentarilyopened when the pump 87 is started until the pump motor 88 has reachedits operating speed. At this time also,.the control valve 77 is open andthat portion of the flow line 70 between the closed flow-line controlvalve 74 and the fluidadmitting means 20 will be filled with well borefluids at the hydrostatic pressure at the depths at which the tool 10 isthen situated.

When the tool 10 is at a selected operating depth, the switches 23 and24 are advanced to their third positions 27. Then, once the pump 87 hasreached its rated operating speed, the hydraulic pressure in the outputline 90 will rapidly rise to its selected maximum operating pressure asdetermined by the maximum or off setting of the pressure switch 101. Asthe pressure progressively rises, the control system will successivelyfunction at selected intermediate pressure levels for sequentiallyoperating the several control valves 105-108 as described fully in theaforementioned copending application Ser. No. 313,235 filed Dec. 8,1972.

Turning now to FIG. 3, selected portions of the control system 15 andvarious components of the tool 10 are schematically represented toillustrate the operation of the tool at about the time that the pressurein the hydraulic output line 90 reaches its lowermost intermediatepressure level. To facilitate an understanding of the operation of thetool 10 and the control system 15 at this point in its operating cycle,only those components which are then operating are shown in FIG. 3.

At this time, since the control switch 23 (FIG. 1) is in its thirdposition 27, the solenoid valves 98 and 104 will be open; and, since thehydraulic pressure in the set" line 96 has not yet reached the upperpressure limit as determined by the pressure switch 101, the pump motor88 will be operating. Since the control valve 105 (not shown in FIG. 3)is closed, the highpressure section 127 of the set line 96 will still beisolated from the low-pressure section 124. Simultaneously, thehydraulic fluid contained in the forward pressure chambers of the pistonactuators 39, 40, 43 and 44 will be displaced (as shown by the arrows asat 131) to the retract line 97 and returned to the reservoir 89 -by wayof the open solenoid valve 104. These actions will, of course, cause thewall-engaging member 38 as well as the sealing pad 41 to be respectivelyextended in opposite lateral directions until each has moved into firmengagement with the opposite sides of the borehole 11.

It will be noticed in FIG. 3 that hydraulicfluid will be admitted by wayof branch hydraulic lines 132 and 133 to the enclosed annular chamber 53to the rear of the enlarged-diameter portion 52 of the fluid-admittingmember 45. At the same time, hydraulic fluid from the piston chamber 54ahead of the enlarged-diameter portion 52 will be discharged by way ofbranch hydraulic lines 134 and 135 to the retract line 97.forprogressively moving the fluid-admitting member 45 forwardly in relationto the sealing member 41 until the nose of the fluid-admitting member 45engages the wall of the borehole 11 and then halts. The sealing pad 41is then urged forwardly in relation the now-halted tubular member 45until the pad sealingly engages the borehole wall for packing-off orisolating the isolated wall portion from the well bore fluids. In thismanner, mudcake immediately ahead of the fluid-admitting member 45 willbe displaced radially away from the nose of the fluid-admitting memberso as to minimize the quantity of unwanted mudcake which willsubsequently be admitted into the fluid-admitting means 20. Thoseskilled in the art will appreciate the significance of this uniquearrangement.

It should also be noted that although the pressured hydraulic fluid isalso admitted at this time into the forward piston chamber 66 betweenthe sealing members 62 and 64 on the valve member 55, the valve memberis temporarily prevented from moving rearwardly in relation to the innerand outer tubular members 45 and 46 inasmuch as the control valve 106(not shown in FIG. 3) is still closed thereby temporarily trapping thehydraulic fluid in the rearward piston chamber 65 to the rear of thevalve member. The significance of this delay in the retraction of thevalve member 55 will be subsequently explained.

As also illustrated in FIG. 3, the hydraulic fluid in the low-pressuresection 124 of the set" line 96 will also be directed by way ofa branchhydraulic line 136 to the piston actuator 86. This will, of course,result in the displacement piston 85 being elevated as the hydraulic'fluid from the piston actuator is returned to the retract line 97 byway of a branch hydraulic conduit 137. As will be appreciated, elevationof the displacement piston 85 in the expansion chamber 84 will beeffective for significantly decreasing the pressure initially existingin the isolated portions of the branch line 83 and the flow line betweenthe still-closed flow-line control valve 74 and the still-closed chambercontrol valves 75 and 76 (not shown in FIG. 3). The purpose of thispressure reduction will be subsequently explained.

Once the wall-engaging member 38, the sealing pad 41 and thefluid-admitting member 45 have respectively reached their extendedpositions as illustrated in FIG. 3, it will be appreciated that thehydraulic pressure delivered by the pump 87 will again rise. Then, oncethe pressure in the output line 90 has reached its second intermediatelevel of operating pressure, the control valve 106 will open in responseto this pressure level to now discharge the hydraulic fluid previouslytrapped in the piston chamber 65 to the rear of the valve member 55 backto the reservoir 89.

As illustrated in FIG. 4, once the control valve 106 opens, thehydraulic fluid will be displaced from the rearward piston chamber 65 byway of branch hydraulic lines 138, 139 and to the retract line 97 aspressured hydraulic fluid from the set line 96 surges into the pistonchamber 66 ahead of the enlargeddiameter portion 61 of the valve member55. This will, of course, cooperate to rapidly drive the valve member 55rearwardly in relation to the now-halted fluidadmitting member 45 forestablishing fluid or pressure communication between the isolatedportion of the earth formation 12 and the flow passages 57 and 60 in thevalve member by way of the filter screen 69. This unique flexibility ofoperation provided by the fluidadmitting means 20 of the presentinvention is, of course, highly significant.

Although this is not fully illustrated in FIG. 4, it will be recalledfrom FIGS. 2A and 28 that the control valves 74-76 are initially closed'to isolate the lower portion of the flow line 70 between these valvesas well as the branch line 83 leading to the pressure-reduction chamber84. However, the flow-line pressureequalizing control valve 77 willstill be open at the time the control valve 106 opens to retract thevalve member 55 as depicted in FIG. 4. Thus, as the valve member 55progressively uncovers the filtering screen 69, well bore fluids at apressure greater than that of any connate fluids which may be present inthe isolated earth formation 12 will be introduced into the upperportion of the flow line 70 and, by way of the flexible conduit member71, into the rearward end of the tubular member 58. As thesehigh-pressure well bore fluids pass into the annular space 67 around thefiltering screen 69, they will be forcibly discharged (as shown by thearrows 140) from the forward end of the fluid-admitting member 45 forwashing away any plugging materials such as mudcake or the like whichmay have become deposited on the internal surface of the filteringscreen when the valve member 55 first uncovers the screen. Thus, thecontrol system 15 is operative for providing a momentary outward surgeor reverse flow of well bore fluids for cleansing the filtering screen69 of unwanted debris or the like before a sampling or testing operationis commenced.

It will be appreciated that once the several components of theformation-testing tool and the control system have reached theirrespective positions as depicted in FIG. 4, the hydraulic pressure inthe output line 90 will again quickly increase to its next intermediatepressure level. Once the pump 87 has increased the hydraulic pressure inthe output line 90 to this next predetermined intermediate pressurelevel, the control valve 105 will selectively open as depicted in FIG.5A. As seen there, opening of the control valve 105 will be effectivefor now supplying hydraulic fluid to the highpressure section 127 of theset line 96 and two branch conduits 141 and 142 connected thereto forsuccessively closing the control valve 77 and then opening the controlvalve 74.

In this manner, as depicted by the several arrows at 143 and 144,hydraulic fluid at a pressure representative ofthe intermediateoperating level will be supplied by way of a typical check valve 145 tothe upper portion of the piston cylinder 146 of the normally-open Icontrol valve 77 as fluid is exhausted from the lower portion thereof byway of a conduit 147 coupled to the "retract" line 97. This will, ofcourse, be effective for closing the valve member 82 so as to now blockfurther communication between the flow line 70 and the well bore fluidsexterior of the tool 10. Simultaneously, the hydraulic fluid will alsobe admitted into the lower portion of the piston cylinder 148 of thecontrol valve 74. By arranging the biasing spring 81 for thenormallyopen control valve 77 to be somewhat weaker than the biasingspring 149 for the normally-closed control valve 74, the second valvewill be momentarily retained in its closed position until the firstvalve has had time to close. Thus, once the valve 77 closes, as thehydraulic fluid enters the lower portion of the piston chamber 148 ofthe control valve 74, the valve member 150 will be opened as hydraulicfluid is exhausted from the upper portion of the chamber through atypical check valve 151 and a branch return line 152 coupled to theretract" line 97.

It will be appreciated, therefore, that with the tool 10 in the positiondepicted in FIG. 5, the flow line is now isolated from the well borefluids and is in communication with the isolated portion of the earthformation 12 by way of the flexible conduit 71. It will also be recalledfrom the preceding discussion of FIG. 3 that the branch flow line 83 aswell as the portion of the main flow line 70 between the flow-linecontrol valve 74 and the sample chamber control valves and 76 werepreviously expanded by the upward movement of the displacement piston inthe reduced-volume chamber 84. Thus, upon opening of the flow-linecontrol valve 74, the isolated portion of the earth formation 12 will becommunicated with the reducedpressure space represented by thepreviously-isolated portions of the flow line 70 and the branch conduit83.

Of particular interest to the present invention, it should be furthernoted that should the formation 12 be relatively unconsolidated, therearward movement of the valve member 55 in cooperation with the forwardmovement of the fluid-admitting member 45 will allow only those looseformation materials displaced by the advancement of the fluid-admittingmember into the formation to enter the fluid-admitting member. This isto say, the fluid-admitting member 45 can advance into the formation 12only by displacing loose formation materials; and, since the spaceopened within the forward end of the fluid-admitting member by therearward displacement of the valve member 55 is the only place intowhich the loose formation materials can enter, further erosion of theformation materials will be halted once the fluid-admitting member hasbeen filled with loose materials as shown in FIG. 5B. On the other hand,should a formation interval which is being tested be relativelywell-compacted, the advancement of the fluid-admitting member 45 will berelatively slight with its nose making little or no penetration into theisolated earth formation. It will, of course, be appreciated that thenose of the fluid-admitting member 45 will be urged outwardly withsufficient force to at least penetrate the mudcake which typically linesthe borehole walls adjacent to permeable earth formations. In thissituation, however, the forward movement of the fluid-admitting member45 will be unrelated to the rearward movement of the valve member 55 asit progressively uncovers the filtering screen 69. In either case, thesudden opening of the valve 74 will cause mudcake to be pulled to therear of the screen 69 to leave it clear for the subsequent passage ofconnate fluids.

As best seen in FIGS. 5A and 58, therefore, should there by anyproducible connate fluids in the isolated earth formation 12, theformation pressure will be effective for displacing these connate fluidsby way of the fluid-admitting means 20 into the flow line until suchtime that the lower portion of the flow line 70 and the branch conduit83 are filled and pressure equilibrium is established in the entire flowline. By arranging a typical pressuremeasuring transducer, as at 153(or, if desired, one or more other suitable transducers) in the flowline 70, one or more measurements representative of the characteristicsof the connate fluids and the formation 12 may be transmitted to thesurface by a conductor 154 and, if desired, recorded on the recordingapparatus 16 (FIG. 1). The pressure measurements provided by thetransducer 153 will, of course, permit the operator at the surface toreadily determine the formation pressure as well as to obtain one ormore indications representative of the potential producing ability ofthe formation 12. The various techniques for analyzing formationpressures as well known in the art and are, therefore, of nosignificance to understanding the present invention.

The measurements provided by the pressure transducer 153 at this timewill indicate whether the sealing pad 41 has, in fact, establishedcomplete sealing engagement with the earth formation 12 inasmuch as theexpected formation pressures will be recognizably lower than thehydrostatic pressure of the well bore fluids at the particular depthwhich the tool 10 is then situated. This ability to determine theeffectiveness of the sealing engagement will, of course, allow theoperator to retract the wall-engaging member 38 and the sealing pad 41without having to unwittingly or needlessly continue the remainder ofthe complete operating sequence.

Assuming, however, that the pressure measurements provided by thepressure transducer l53show that the sealing pad 41 is firmly seated,the operator may leave the formation-testing tool 10 in the positionshown in FIGS. SA and B as long as it is desired to observe as well asrecord the pressure measurements. As a result, the operator candetermine such things as the time required for the formation pressure toreach equilibrium as well as the rate of increase and thereby obtainvaluable information indicative of various characteristics of the earthformation 12 such as permeability and porosity. Moreover, with the newand improved tool 10, the operator can readily determine if collectionof a fluid sample is warranted.

Once the several components of the tool and the control system 15 havemoved to their respective positions shown in FIGS. 5A and 5B, thehydraulic pressure will again rise until such time that the set linepressure switch 101 operates to halt the hydraulic pump 87. Inasmuch asthe pressure switch 101 has a selected operating range, in the typicalsituation the pump 87 will be halted shortly after the control valve 77closes and the control valve 74 opens. At this point in the operatingcycle of the tool 10, once a sufficient number of pressure measurementshave been obtained, a decision can be made whether it is advisable toobtain one or more samples of the producible connate fluids present inthe earth formation 12. lf such samples are not desired, the operatorcan simply operate the control switches 23 and 24 for retracting thewall-engaging member 38 as well as the sealing pad 41 without furtherado. This freedom of action is, of course, possible by virtue of theflexibility of operation of the new and improved fluid-admitting means20.

On the other hand, should a fluid sample be desired, the controlswitches 23 and 24 (FIG. 1) are advanced to their next or so-calledsample positions 28 to open, for example, a solenoid valve 155 forcoupling pressured hydraulic fluid from the high-pressure section 127 ofthe set line 96 to the piston actuator 156 of the sample chamber controlvalve 75. This will, of course, be effective for opening the controlvalve 75 to admit connate fluids through the flow line 70 and the branchconduit 72 into the sample chamber 21. If desired, a chamber selectionswitch 157 in the surface portion of the system 15 could also be movedfrom its first sample position 158 to its so-called second sampleposition 159 (FIG. 1) to energize the solenoid valve 160 for opening thecontrol valve 76 to also admit connate fluids into the other samplechamber 22. in either case, one or more samples of the connate fluidswhich are present in the isolated earth formation 12 can be selectivelyobtained by the new and improved tool 10.

Upon moving the control switches 23 and 24 to their so-calledsample-trapping" positions 29, the pump 87 will again be restarted. Oncethe pump 87 has reached operating speed, it will commence to operatemuch in the same manner as previously described and the hydraulicpressure in the output line 90 will again begin rising with momentaryhalts at various intermediate pressure levels.

Accordingly, when the control switches 23 and 24 have been placed intheir sample trapping positions 29, the solenoid valve 99 will open toadmit hydraulic fluid into the retract" line 97. By means of theelectrical conductor 103a, however, the pressure switch 103 is enabledand the pressure switch 102 is disabled so that in this position of thecontrol switches 23 and 24 the maximum operating pressure which the pump87 can initially reach is limited to the pressure at the operatingpressure level determined by the pressure switch 103. Thus, by arrangingthe control valve 108 to open in response to a hydraulic pressurecorresponding to this predetermined pressure level, hydraulic fluid inthe high-pressure section 127 of the set line 96 will be returned to thereservoir 89 by means of the return line 94. As the hydraulic fluid inthe high-pressure section 127 returns to the reservoir 89, the pressurein this portion of the set" line 96 will be rapidly decreased to closethe control valve once the pressure in the line is sufficient to holdthe valve open. Once the control valve 105 closes, the pressureremaining in the lowpressure section 124 of the set line 96 will remainat a reduced pressure which is nevertheless effective for retaining thewall-engaging member 38 and the sealing pad 41 fully extended.

As the hydraulic fluid is discharged from the lower portion of thepiston actuator 156 by way of the stillopen solenoid valve and fluidfrom the retract" line 97 enters the upper portion of the actuator byway of the branch line 161, the chamber control valve 75 will close totrap the sample of connate fluids which is then present in the samplechamber 21. Similarly, should there also be a fluid sample in the othersample chamber 22, the control valve 76 can also be readily closed byoperating the switch 157 to reopen the solenoid valve 160. Closure ofthe control valve 75 (as well as the valve 76) will, of course, beeffective for trapping any fluid samples collected in one or the otheror both of the sample chambers 21 and 22.

Once the control valve 75 (and, if necessary, the control valve 76) hasbeen reclosed, the control switches 23 and 24 are moved to their next orso-called retract switching positions 30 for initiating the simultaneousretraction of the wall-engaging member 38 and the sealing pad 14. Inthis final position of the control switch 24, the pressure switch 103 isagain rendered inoperative and the pressure switch 102 is enabled so asto now permit the hydraulic pump 87 to be operated at full ratedcapacity for attaining hydraulic pressures greater than the firstintermediate operating level in the retractf cycle. Once the pressureswitch 103 has again been disabled, the pressure switch 102 will nowfunction to operate the pump 87 so that the pressure will now quicklyrise until it reaches the next operating level.

At this point, hydraulic fluid will be supplied through the retract line97 and the branch hydraulic line 147 for reopening thepressure-equalizing control valve 77 to admit well bore fluids into theflow line 70. Opening of the pressure-equalizing valve 77 will admitwell bore fluids into the isolated space defined by the sealing pad 41so as to equalize the pressure differential existing across the pad.Hydraulic fluid displaced from the upper portion of the piston chamber146 of the control valve 77 will be discharged through a typical reliefvalve 161 which is arranged to open only in response to pressures equalor greater than that of this present operating level. The hydraulicfluid displaced from the piston chamber 146 through the relief valve 161will be returned to the reservoir 89 by way of the branch hydraulic line141, the high-pressure section 127 of the set line 96, the still-opencontrol valve 108, and the return line 94.

When the hydraulic pressure in the output line 90 has either reached thenext operating level or, if desired, a still-higher level, pressuredhydraulic fluid in the retract" line 97 will reopen the control valve107 to communicate the low-pressure section 124 of the set" line 96 withthe reservoir 89. When this occurs, hydraulic fluid in the retract linewill be admitted to the retract side of the several piston actuators 39,40, 43 and 44. Similarly, the pressured hydraulic fluid will also beadmitted into the annular space 54 in front of the enlarged-diameterpiston portion 52 for retracting the fluid-admitting member 45 as wellas into the annular space 66 for returning the valve member 55 to itsforward position. hydraulic fluid exhausted from the several pistonactuators 39, 40, 43 and 44 as well as the piston chambers 54 and 66will be returned directly to the reservoir 89 by way of thehigh-pressure section 124 of the set line 96 and the contron valve 107.This action will, of course, retract the wall-engaging mem ber 38'aswell as the sealing pad 41 against the tool body 18 to permit the toolto be either repositioned in the well bore 11 or returned to the surfaceif no further testing is desired.

It should be noted that although there is an operating pressure appliedto the upper portion of the piston cylinder 148 for the flow-linecontrol valve 74 at the time that the control valve 77 is reopened, anormally-closed relief valve 162 which is paralleled with the checkvalve 151 is held in a closed position until the increasing hydraulicpressure developed by the pump 87 exceeds the operating level used toretract the wall-engaging member 38 and the sealing pad 41. At thispoint in the operating sequence of the new and improved tool 10, theflow-line control valve 74 will be reclosed.

The pump 87 will, of course, continue to operate until such time thatthe hydraulic pressure in the output line 90 reaches the upper limitdetermined by the setting of the pressure switch 102. At some convenienttime thereafter, the control switches 23 and 24 are again returned totheir initial or off" positions 25 for halting further operation of thepump motor 88 as well as reopening the solenoid valve 104 to againcommunicate the retract line 97 with the fluid reservoir 89. Thiscompletes the operating cycle of the new and improved tool l0.

Accordingly, it will be appreciated that the fluidadmitting means 20 ofthe present invention enable the new and improved tool 10 to beselectively operated as required for meeting any situation which may bereasonably expected to occur during a formation-testing operation. Forexample, with the formation-sampling apparatus disclosed in US. Pat. No.3,653,436, once operation of the tool shown there is initiated, furthersampling operations cannot be conducted with removing the tool andreconditioning various components thereof. This is, of course in clearcontrast to the versatility permitted by the selectively-operablefluidadmitting means 20 of the present invention and the new andimproved tool 10.

While only a particular embodiment of the present invention has beenshown and described, it is apparent that changes and modifications maybe made without departing from this invention in its broader aspects;and, therefore, the aim in the appended claims is to cover all suchchanges and modifications as fall within the true spirit and scope ofthis invention.

What is claimed is:

l. Formatiomtesting apparatus adapted for suspension in a boreholetraversing earth formations and comprising:

a body having a first fluid passage adapted to receive connate fluids;fluid-admitting means on said body and including a fluid-sampling memberhaving a tubular forward portion adapted to be engaged with a boreholewall for isolating a surface thereof from well bore fluids;

means selectively operable for positioning said fluidsampling memberagainst a borehole wall to establish communication with earth formationstherebeyond;

first means adapted for limiting the entrance of plugging materials intosaid first fluid passage including a second fluid passage in saidfluid-sampling member and coupled to said first fluid passage, andfiltering means cooperatively arranged on a wall of said fluid-samplingmember between said second fluid passage and with tubular forwardportion for retaining plugging materials within said fluidsamplingmember as filtered connate fluids pass through said filtering means andenter said second fluid passage;

second means adapted for controlling the entrance of plugging materialsand connate fluids into said fluid-sampling member and including a valvemember coaxially arranged in said fluid-sampling member for movementbetween an advanced position within said tubular forward portionblocking communication into said fluid-sampling member and a retractedposition to the rear of said tubular forward portion for uncovering saidfiltering means and defining a space for receiving plugging materialsentering said tubular forward portion; and valve-control meanscooperatively arranged for selectively moving said valve member back andforth between its said advanced and retracted positions.

2. The formation-testing apparatus of claim 1 wherein said second fluidpassage includes an annular chamber formed around an intermediateinterior wall portion of said fluid-sampling member between saidadvanced and retracted positions of said valve member; and saidfiltering means include a tubular screen coaxially mounted in saidfluid-sampling member around said annular chamber.

3. The formation-testing apparatus of claim 1 further including:

sealing means cooperatively arranged on said fluidadmitting means aroundsaid tubular forward portion and adapted for packing-off a borehole wallaround said tubular forward portion. 4. The formation-testing apparatusof claim 1 further including:

means cooperatively mounting said fluid-sampling member on said body formovement relative thereto between a laterally-extended position and aretracted position; and

control means cooperatively arranged for selectively moving saidfluid-sampling member back and forth between its said extended andretracted positions.

5. The formation-testing apparatus of claim 1 further including:

sample-receiving means on said body and adapted for receiving filteredconnate fluids entering fluid passages; and

control means cooperatively arranged for selectively coupling saidsample-receiving means to said first fluid passage.

6. Formation-testing apparatus adapted for suspension in a boreholetraversing earth formations and comprising:

a body having a chamber adapted to receive connate fluid-admitting meanson said body and including a tubular fluid-sampling member having aforward portion adapted to be engaged with a borehole wall for isolatinga surface thereof from well bore fluids and receiving connate fluidsfrom earth formations therebeyond;

means selectively operable for positioning said fluidsampling memberagainst a borehole wall and including first piston means cooperativelyarranged on said body for movement between a first position to engagesaid fluid-sampling member with a borehole wall and a second position todisengage said fluid-sampling member from a borehole wall; meanscoupling said fluid-sampling member to said chamber and includingfluid-passage means between said chamber and an intermediate portion ofsaid fluid-sampling member, and filtering means cooperatively arrangedon said intermediate portion of said fluid-sampling member for limitingthe entrance of loose materials into said fluid-passage means; U meansfor controlling the admission of connate fluids and loose materials intosaid fluid-sampling membeer and including a valve member coaxiallyarranged in said fluid-sampling member for movement between an advancedposition in said forward portion for blocking communication into saidfluidsampling member and a retracted position to the rear of saidintermediate portion for exposing said filtering means, and secondpiston means cooperatively coupled to said valve member and adapted Vfor movement between a first position to place said valve member in itssaid advanced position and a second position to place said valve memberin its said retracted position; and

control means cooperatively coupled to said first and second pistonmeans for selectively moving said LII 18 first and second piston meansback and forth between their respective positions. 7. Theformation-testing apparatus of claim 6 further including:

pressure-monitoring means for providing indications at the surfaceindicative of the pressure of connate fluids in said chamber. 8. Theformation-testing apparatus of claim 6 further including:

valve means in said fluid-passage means and cooperatively coupled tosaid control means for selectively entrapping connate fluids in saidchamber.

9. The formation-testing apparatus of claim 6 further including:

a wall-engaging member movably mounted on said body on the opposite sidethereof from said forward portion of said fluid-sampling member andcooperatively coupled to said first piston means for movement therebybetween an extended wallengaging position and a retracted positionagainst said opposite body side.

10. The formation-testing apparatus of claim 6 further including:

ther including:

a wall-engaging member movably mounted on said body on the opposite sidethereof and cooperatively coupled to said first piston means formovement thereby between an extended wall-engaging position and aretracted position against said opposite body side upon movement of saidfirst piston means between said first and second positions thereof.

12. Formation-testing apparatus adapted for suspension in a boreholetraversing earth formations and comprising:

a body having a chamber adapted to receive connate fluids;

fluid-admitting means on said body and including a tubularfluid-sampling member cooperatively arranged for lateral movement inrelation to said body between retracted and extended positions,fluid-passage means between said fluid-sampling member and said chamber,a tubular filter coaxially arranged on said fluid-sampling membercovering said fluid-passage means for limiting the entrance of loosematerials into said fluid-passage means, and first. piston means coupledto said fluidsampling member and cooperatively arranged for moving saidfluid-sampling member back and forth between its said retracted andextended positions;

means for controlling the admission of connate fluids and loosematerials into said fluid-sampling member and including a valve membercoaxially disposed in said fluid-sampling member and cooperativelyarranged for movement through said tubular filter between an advancedclosed position where said valve member is substantially sealinglyengaged with the forward portion of said fluidsampling member ahead ofsaid tubular filter and a retracted open position to the rear thereofwhere said tubular filter is in communication with said forward portion,and second piston means coupled to said valve member and cooperativelyarranged for moving said valve member back and forth between its saidopen and closed positions; and control means cooperatively arranged forselectively operating said first and second piston means to move saidfluid-sampling member and said valve member between their respectivesaid positions.

13. The formation-testing apparatus of claim 12 further including:

a wall-engaging member movably mounted on said body on the opposite sidethereof from said fluidadmitting means and cooperatively arranged formovement between a retracted position against said opposite body sideand an extended wallengaging position for urging said fluid-admittingmeans against a borehole wall; and

third piston means cooperatively coupled to said wall-engaging memberand said control means for selectively moving said wall-engaging memberbetween its said retracted and extended positions.

14. The formation-testing apparatus of claim 12 wherein saidfluid-admitting means further include:

packoff means cooperatively mounted on said body and around said forwardportion of said fluidsampling member for establishing sealing engagementwith a borehole wall to isolate said forward portion of saidfluid-sampling member from borehole fluids.

15. The formation-testing apparatus of claim 14 further including:

a wall-engaging member movably mounted on said body on the opposite sidethereof from said fluidadmitting means and cooperatively arranged formovement between a retracted position against said opposite body sideand an extended wallengaging position for urging said fluid-admittingmeans against a borehole wall; and

third piston means cooperatively coupled to said wall-engaging memberand said control means for selectively moving said wall-engaging memberbetween its said retracted and extended positions.

16. The formation-testing apparatus of claim 14 further including:

means including a movable member cooperatively coupling said packoffmeans and said fluidsampling member to said body for movement relativeto one side thereof between a laterallyextended position and a retractedposition; and

third piston means cooperatively coupled to said movable member and saidcontrol means for selectively moving said movable member between itssaid retracted and extended positions.

17. The formation-testing apparatus of claim 16 further including:

a wall-engaging member movably mounted on said body on the opposite sidethereof from said fluidadmitting means and cooperatively arranged formovement between a retracted position against said opposite body sideand an extended wallengaging position for urging said fluidadmittingmeans against a borehole wall; and

fourth piston means cooperatively coupled to said wall-engaging memberand said control means for selectively moving said wall-engaging memberbetween its said retracted and extended positions.

18. The formation-testing apparatus of claim 17 wherein said controlmeans are cooperatively arranged for operating said third and fourthpiston means in unison.

19. The formation-testing apparatus of claim 16 wherein said forwardportion of said fluid-sampling member projects outwardly beyond saidpackoff means in said retracted position of said fluid-sampling memberfor engaging a borehole wall in advance of said packoff means.

20. The formation-testing apparatus of claim 12 further including:

pressure-monitoring means for providing indications at the surfaceindicative of the pressure of connate fluids in said chamber.

21. The formation-testing apparatus of claim 12 further including:

valve means in said fluid-passage means and cooperatively coupled tosaid control means for selectively entrapping connate fluids in saidchamber.

1. Formation-testing apparatus adapted for suspension in a boreholetraversing earth formations and comprising: a body having a first fluidpassage adapted to receive connate fluids; fluid-admitting means on saidbody and including a fluidsampling member having a tubular forwardportion adapted to be engaged with a borehole wall for isolating asurface thereof from well bore fluids; means selectively operable forpositioning said fluid-sampling member against a borehole wall toestablish communication wiTh earth formations therebeyond; first meansadapted for limiting the entrance of plugging materials into said firstfluid passage including a second fluid passage in said fluid-samplingmember and coupled to said first fluid passage, and filtering meanscooperatively arranged on a wall of said fluid-sampling member betweensaid second fluid passage and with tubular forward portion for retainingplugging materials within said fluid-sampling member as filtered connatefluids pass through said filtering means and enter said second fluidpassage; second means adapted for controlling the entrance of pluggingmaterials and connate fluids into said fluid-sampling member andincluding a valve member coaxially arranged in said fluidsampling memberfor movement between an advanced position within said tubular forwardportion blocking communication into said fluid-sampling member and aretracted position to the rear of said tubular forward portion foruncovering said filtering means and defining a space for receivingplugging materials entering said tubular forward portion; andvalve-control means cooperatively arranged for selectively moving saidvalve member back and forth between its said advanced and retractedpositions.
 2. The formation-testing apparatus of claim 1 wherein saidsecond fluid passage includes an annular chamber formed around anintermediate interior wall portion of said fluid-sampling member betweensaid advanced and retracted positions of said valve member; and saidfiltering means include a tubular screen coaxially mounted in saidfluid-sampling member around said annular chamber.
 3. Theformation-testing apparatus of claim 1 further including: sealing meanscooperatively arranged on said fluid-admitting means around said tubularforward portion and adapted for packing-off a borehole wall around saidtubular forward portion.
 4. The formation-testing apparatus of claim 1further including: means cooperatively mounting said fluid-samplingmember on said body for movement relative thereto between alaterally-extended position and a retracted position; and control meanscooperatively arranged for selectively moving said fluid-sampling memberback and forth between its said extended and retracted positions.
 5. Theformation-testing apparatus of claim 1 further including:sample-receiving means on said body and adapted for receiving filteredconnate fluids entering fluid passages; and control means cooperativelyarranged for selectively coupling said sample-receiving means to saidfirst fluid passage.
 6. Formation-testing apparatus adapted forsuspension in a borehole traversing earth formations and comprising: abody having a chamber adapted to receive connate fluids; fluid-admittingmeans on said body and including a tubular fluid-sampling member havinga forward portion adapted to be engaged with a borehole wall forisolating a surface thereof from well bore fluids and receiving connatefluids from earth formations therebeyond; means selectively operable forpositioning said fluid-sampling member against a borehole wall andincluding first piston means cooperatively arranged on said body formovement between a first position to engage said fluid-sampling memberwith a borehole wall and a second position to disengage saidfluid-sampling member from a borehole wall; means coupling saidfluid-sampling member to said chamber and including fluid-passage meansbetween said chamber and an intermediate portion of said fluid-samplingmember, and filtering means cooperatively arranged on said intermediateportion of said fluid-sampling member for limiting the entrance of loosematerials into said fluid-passage means; means for controlling theadmission of connate fluids and loose materials into said fluid-samplingmember and including a valve member coaxially arranged in saidfluid-sampling member for movement between an advanced position in saidforward portion for blocking communication into saId fluid-samplingmember and a retracted position to the rear of said intermediate portionfor exposing said filtering means, and second piston means cooperativelycoupled to said valve member and adapted for movement between a firstposition to place said valve member in its said advanced position and asecond position to place said valve member in its said retractedposition; and control means cooperatively coupled to said first andsecond piston means for selectively moving said first and second pistonmeans back and forth between their respective positions.
 7. Theformation-testing apparatus of claim 6 further including:pressure-monitoring means for providing indications at the surfaceindicative of the pressure of connate fluids in said chamber.
 8. Theformation-testing apparatus of claim 6 further including: valve means insaid fluid-passage means and cooperatively coupled to said control meansfor selectively entrapping connate fluids in said chamber.
 9. Theformation-testing apparatus of claim 6 further including: awall-engaging member movably mounted on said body on the opposite sidethereof from said forward portion of said fluid-sampling member andcooperatively coupled to said first piston means for movement therebybetween an extended wall-engaging position and a retracted positionagainst said opposite body side.
 10. The formation-testing apparatus ofclaim 6 further including: means cooperatively coupling saidfluid-sampling member to said body for movement relative to one sidethereof between a laterally-extended position and a retracted position;and means cooperatively coupling said fluid-sampling member to saidfirst piston means for movement thereby between its saidlaterally-extended position and its said retracted position uponmovement of said first piston means between said first and secondpositions thereof.
 11. The formation-testing apparatus of claim 10further including: a wall-engaging member movably mounted on said bodyon the opposite side thereof and cooperatively coupled to said firstpiston means for movement thereby between an extended wall-engagingposition and a retracted position against said opposite body side uponmovement of said first piston means between said first and secondpositions thereof.
 12. Formation-testing apparatus adapted forsuspension in a borehole traversing earth formations and comprising: abody having a chamber adapted to receive connate fluids; fluid-admittingmeans on said body and including a tubular fluid-sampling membercooperatively arranged for lateral movement in relation to said bodybetween retracted and extended positions, fluid-passage means betweensaid fluid-sampling member and said chamber, a tubular filter coaxiallyarranged on said fluid-sampling member covering said fluid-passage meansfor limiting the entrance of loose materials into said fluid-passagemeans, and first piston means coupled to said fluid-sampling member andcooperatively arranged for moving said fluid-sampling member back andforth between its said retracted and extended positions; means forcontrolling the admission of connate fluids and loose materials intosaid fluid-sampling member and including a valve member coaxiallydisposed in said fluid-sampling member and cooperatively arranged formovement through said tubular filter between an advanced closed positionwhere said valve member is substantially sealingly engaged with theforward portion of said fluid-sampling member ahead of said tubularfilter and a retracted open position to the rear thereof where saidtubular filter is in communication with said forward portion, and secondpiston means coupled to said valve member and cooperatively arranged formoving said valve member back and forth between its said open and closedpositions; and control means cooperatively arranged for selectivelyoperating said first and second piston means to move said fluid-samplingmember and said valve member between theIr respective said positions.13. The formation-testing apparatus of claim 12 further including: awall-engaging member movably mounted on said body on the opposite sidethereof from said fluid-admitting means and cooperatively arranged formovement between a retracted position against said opposite body sideand an extended wall-engaging position for urging said fluid-admittingmeans against a borehole wall; and third piston means cooperativelycoupled to said wall-engaging member and said control means forselectively moving said wall-engaging member between its said retractedand extended positions.
 14. The formation-testing apparatus of claim 12wherein said fluid-admitting means further include: packoff meanscooperatively mounted on said body and around said forward portion ofsaid fluid-sampling member for establishing sealing engagement with aborehole wall to isolate said forward portion of said fluid-samplingmember from borehole fluids.
 15. The formation-testing apparatus ofclaim 14 further including: a wall-engaging member movably mounted onsaid body on the opposite side thereof from said fluid-admitting meansand cooperatively arranged for movement between a retracted positionagainst said opposite body side and an extended wall-engaging positionfor urging said fluid-admitting means against a borehole wall; and thirdpiston means cooperatively coupled to said wall-engaging member and saidcontrol means for selectively moving said wall-engaging member betweenits said retracted and extended positions.
 16. The formation-testingapparatus of claim 14 further including: means including a movablemember cooperatively coupling said packoff means and said fluid-samplingmember to said body for movement relative to one side thereof between alaterally-extended position and a retracted position; and third pistonmeans cooperatively coupled to said movable member and said controlmeans for selectively moving said movable member between its saidretracted and extended positions.
 17. The formation-testing apparatus ofclaim 16 further including: a wall-engaging member movably mounted onsaid body on the opposite side thereof from said fluid-admitting meansand cooperatively arranged for movement between a retracted positionagainst said opposite body side and an extended wall-engaging positionfor urging said fluid-admitting means against a borehole wall; andfourth piston means cooperatively coupled to said wall-engaging memberand said control means for selectively moving said wall-engaging memberbetween its said retracted and extended positions.
 18. Theformation-testing apparatus of claim 17 wherein said control means arecooperatively arranged for operating said third and fourth piston meansin unison.
 19. The formation-testing apparatus of claim 16 wherein saidforward portion of said fluid-sampling member projects outwardly beyondsaid packoff means in said retracted position of said fluid-samplingmember for engaging a borehole wall in advance of said packoff means.20. The formation-testing apparatus of claim 12 further including:pressure-monitoring means for providing indications at the surfaceindicative of the pressure of connate fluids in said chamber.
 21. Theformation-testing apparatus of claim 12 further including: valve meansin said fluid-passage means and cooperatively coupled to said controlmeans for selectively entrapping connate fluids in said chamber.